Vitamin D

Vitamin D. By David Archibald.

Plants, animals and funghi all have a form of vitamin D. All produce it by exposure to ultraviolet radiation from the Sun, specifically UVB.

The amount of Vitamin D a human will produce per day under optimum conditions is about 0.25 milligrams [10,000 IU] in about half an hour of sun exposure. Staying out in the sun longer doesn’t produce any more. …

Vitamin D deficiency results in higher rates of hypertension, autoimmune diseases, diabetes, cancer, and viral infections. …

Vitamin D can be far more efficient than higher level treatments. For example, in a 2014 study of flu vaccinations, it was found that 71 people would need to be vaccinated to prevent one case of influenza which translates to a 1.4% response rate. In contrast, a 2010 study of 334 school-aged children found that, compared to a placebo, 1,200 IU a day of vitamin D over four months achieved a risk reduction of 7.8% against the flu virus. …

Pfizer says you have to be joking:

A daily dose of 10,000 IU is 0.25 of a milligram. … A gram of vitamin D would provide 4,000 doses … at a cost of A$0.0075 per dose. …

Optimum levels:


People living in the tropics normally have a vitamin D blood level in the range of 40 to 80 ng/ml. …



Vitamin D has a half life in the bloodstream of 15 days. Vitamin D is lipophilic and some is stored in fat.



Because vitamin D is known to participate in cell cycle regulation, cellular proliferation and apoptosis, angiogenesis, and molecular cell signaling, it follows that this metabolite is involved in the development and progression of numerous cancers.

In a study of women in Taiwan, it was found that those with a dietary intake of vitamin D of more than 5 µg (200 IU) had a 48% lower incidence of breast cancer than those with an intake of less than 2 µg (80 IU) per day1.

In prostate cancer, a meta-analysis found that every eight ng/ml increase in circulating vitamin D level decreased all-cause mortality by 9% in a nonlinear relationship2. The effect is most pronounced below a vitamin D blood concentration of 40 ng/ml. All-cause mortality is the red line in the following graph:



Most Australians have a blood vitamin D concentration of about 25 ng/ml. If the blood concentration was doubled to 50 ng/ml, the prostate cancer rate would fall 45% from the rate at 25 ng/ml. …


A physiological, safe dose of vitamin D is about 10,000 IU/day. This is the amount our own body produces when exposed to 20-30 minutes to the mid-day sun.

With this daily dose, no precautions or medical supervision is necessary. It is worth noting that the IOM (Institute of Medicine) indicates that 10,000 IU/day is considered the “NOAEL”- No Observed Adverse Effect Level. …

Two cases of overdosing vitamin D due to formulating errors illustrate the inherent safety of vitamin D. A four year old girl with cystic fibrosis was prescribed a daily dose that included 800 IU of vitamin D4. Two and a half months later she presented at hospital with weight loss and other problems. It was found that her daily dose of vitamin D was 8,000,000 IU which is ten thousand times higher than her prescribed dose. Her starting level of serum vitamin D was measured at 30 ng/ml and in hospital at 1,675 ng/ml. In another formulating error5, a patient prescribed 2,000 IU per day was instead given capsules containing 4,000,000 IU per day, two thousand times the prescribed dose. After he presented with worsening of renal function and hypercalcemia and was found to have a serum vitamin D level of 226 ng/ml. The fact that people can survive vitamin D dosing at 2,000 and 10,000 times the prescribed dose speaks volumes to the inherent safety of vitamin D. …


Vitamin D is strongly antiviral and a number of viruses have evolved to suppress the vitamin D receptors on cells. This includes the Epstein-Barr virus1. Covid also responds to vitamin D. Early in the pandemic it was noted that covid incidence correlated with the serum vitamin D level

Level of Vitamin D Covid Incidence
<20 ng/mL 12.5%
30-34 ng/ml 8.1%
 ≥ 55 ng/mL 5.9%

Dogs and cats:

It is accepted that children have stronger immune systems than adults. This could be due to children spending more time outside playing and thus generating vitamin D. It is known that dog owners are healthier than those who don’t own dogs. Apart from a companion animal effect, this is likely to due to dogs knowing that they need to go for a walk for 20 minutes or so each day. Cats don’t provide a similar health benefit to their owners.

Pfizer wants David to shut up:

Vitamin D supplementation at at least 10,000 IU per day has the potential to halve the disease burden in Australia.

Compare and contrast:

hat-tip Stephen Harper